diff --git a/django/contrib/admin/tests.py b/django/contrib/admin/tests.py
index f234fc23938..25610eb1732 100644
--- a/django/contrib/admin/tests.py
+++ b/django/contrib/admin/tests.py
@@ -2,7 +2,7 @@ import os
 from unittest import SkipTest
 
 from django.contrib.staticfiles.testing import StaticLiveServerTestCase
-from django.test import modify_settings
+from django.test import modify_settings, tag
 from django.utils.module_loading import import_string
 from django.utils.translation import ugettext as _
 
@@ -14,6 +14,7 @@ class CSPMiddleware(object):
         return response
 
 
+@tag('selenium')
 @modify_settings(
     MIDDLEWARE_CLASSES={'append': 'django.contrib.admin.tests.CSPMiddleware'},
 )
diff --git a/docs/internals/contributing/writing-code/unit-tests.txt b/docs/internals/contributing/writing-code/unit-tests.txt
index 1de6caacb5d..8ed21549395 100644
--- a/docs/internals/contributing/writing-code/unit-tests.txt
+++ b/docs/internals/contributing/writing-code/unit-tests.txt
@@ -128,6 +128,9 @@ install the selenium_ package into your Python path and run the tests with the
 
    $ ./runtests.py --settings=test_sqlite --selenium admin_inlines
 
+Specifying ``--selenium`` automatically sets ``--tags=selenium`` to run only
+the tests that require selenium.
+
 .. _running-unit-tests-dependencies:
 
 Running all the tests
diff --git a/tests/runtests.py b/tests/runtests.py
index 6fca3dc6a66..b14bc76ed7b 100755
--- a/tests/runtests.py
+++ b/tests/runtests.py
@@ -439,6 +439,10 @@ if __name__ == "__main__":
 
     if options.selenium:
         os.environ['DJANGO_SELENIUM_TESTS'] = '1'
+        if not options.tags:
+            options.tags = ['selenium']
+        elif 'selenium' not in options.tags:
+            options.tags.append('selenium')
 
     if options.bisect:
         bisect_tests(options.bisect, options, options.modules, options.parallel)
diff --git a/tests/view_tests/tests/test_i18n.py b/tests/view_tests/tests/test_i18n.py
index 269a7d70759..c342c85803d 100644
--- a/tests/view_tests/tests/test_i18n.py
+++ b/tests/view_tests/tests/test_i18n.py
@@ -10,7 +10,7 @@ from os import path
 from django.conf import settings
 from django.test import (
     LiveServerTestCase, SimpleTestCase, TestCase, modify_settings,
-    override_settings,
+    override_settings, tag,
 )
 from django.urls import reverse
 from django.utils import six
@@ -260,6 +260,7 @@ skip_selenium = not os.environ.get('DJANGO_SELENIUM_TESTS', False)
 
 
 @unittest.skipIf(skip_selenium, 'Selenium tests not requested')
+@tag('selenium')
 @override_settings(ROOT_URLCONF='view_tests.urls')
 class JavascriptI18nTests(LiveServerTestCase):